OSIRIS-REx Asteroid Sample Collection Activities

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Winston

Lorenzo von Matterhorn
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OSIRIS-REx Asteroid Sample Collection Activities

https://www.asteroidmission.org/?latest-news=watch-osiris-rex-sample-collection-activities
NASA will broadcast coverage of a first for the agency as its Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) mission attempts to collect a sample of asteroid Bennu on Tuesday, Oct. 20, at 6:12 p.m. EDT.

Live coverage of the spacecraft’s descent to the asteroid’s surface for its “Touch-And-Go,” or TAG, maneuver, which will be managed by Lockheed Martin Space near Denver, will begin at 5 p.m. EDT on NASA Television and the agency’s website.

Beginning with an orbit departure maneuver around 1:50 p.m., the full sequence of the complicated engineering feat will be covered on @OSIRISREx, and media and the public can ask questions using the hashtag #ToBennuandBack.


 
They won't know if they "caught" a sample until the photographs are returned over the next day or three. Then they'll repeat a roll maneuver that they did earlier with the sample chamber empty and use physics to estimate the mass of the sample. Cool science!
 
Yes, I have to estimate such things myself, but can't imagine doing it to that level of precision. Consider the spacecraft's mass. The TAGSAM arm is extended. They spin the thing so that the tag arm orbits the center of mass of the spacecraft and make their measurements. Then they get a teensy amount of dirt in the end and spin it again, and calculate the difference in I'm not sure what - probably rotational speed, but sheesh, what's the tolerance on the rotational energy from (assumed) several rocket engines fired simultaneously? Look at us we can't even get delay drilling down pat! :) Anyway, that's designed to determine the change in mass moment of inertia; that change is relatively greater than the change in mass alone, and apparently easier to measure as well.

That's what amazes me, the precision of all of this. It was only orbiting a half-mile up, it made this small de-orbit burn and was descending at speed (along it's trajectory) of only 10 cm (4 inches) per second relative to the asteroid... Yow!
 
Yes, I have to estimate such things myself, but can't imagine doing it to that level of precision. Consider the spacecraft's mass. The TAGSAM arm is extended. They spin the thing so that the tag arm orbits the center of mass of the spacecraft and make their measurements. Then they get a teensy amount of dirt in the end and spin it again, and calculate the difference in I'm not sure what - probably rotational speed, but sheesh, what's the tolerance on the rotational energy from (assumed) several rocket engines fired simultaneously? Look at us we can't even get delay drilling down pat! :) Anyway, that's designed to determine the change in mass moment of inertia; that change is relatively greater than the change in mass alone, and apparently easier to measure as well.

That's what amazes me, the precision of all of this. It was only orbiting a half-mile up, it made this small de-orbit burn and was descending at speed (along it's trajectory) of only 10 cm (4 inches) per second relative to the asteroid... Yow!

Yeah, and the deorbit burn, descent, and subsequent ascent, all used fuel (duh) and changed the mass of the vehicle AFTER the "empty" spin maneuver, so that fuel use (mass change) estimate is laid on top of the change in mass due to picking up the sample. And, I would guess, that the fuel use is considerably greater (perhaps not an order of magnitude) than the 60 grams (60 GRAMS 😮 is 2 ounces, or a stack of 12 nickels) of sample they are hoping for. Worse yet, that estimate needs to be as accurate as possible as they calculate the propellant burns needed to navigate the return trip to earth.
 
I was wondering about the relative positions of Bennu and Earth right now and thought this page from the Perseverance Rover mission might help. If you scroll down the page about halfway you can X out of the Perseverance details, click on the Inner Solar System at the bottom of the frame and you can see what's going on in our neighborhood.

They've put out a nice video of the touch-and-go. As more data is downloaded we should see more.
 
Holy crap that spacecraft was brave to go down there - huge boulders everywhere!

Looks like it did blast up a lot of debris - doughnuts to dollars, they'll bring samples home!

This will land in 2023, I believe, probably be in the Utah desert? Hope the landing sensors are installed the right way up this time! Was it Genesis that crashed?
 
During the post-sample public briefing, I heard it said that they'll be looking for any evidence of a meteor shower on Earth due to the huge amount debris ejected from the asteroid during the sampling process.

NASA's OSIRIS REx Mission Ends Up With More Than It Expected

 
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